[PATCH] perf tools: Enable pre-event inherit setting by config terms

From: Wang Nan
Date: Fri Oct 23 2015 - 05:31:16 EST

This patch allows perf record setting event's attr.inherit bit by
config terms like:

# perf record -e cycles/no-inherit/ ...

So user can control inherit bit for each event separately.

In following example, a.out fork()s in main then do some complex
CPU intensive computations in both of its children.

Basic result with and without inherit:

# perf record -e cycles -e instructions ./a.out
[ perf record: Woken up 9 times to write data ]
[ perf record: Captured and wrote 2.205 MB perf.data (47920 samples) ]
# perf report --stdio
# ...
# Samples: 23K of event 'cycles'
# Event count (approx.): 23641752891
...
# Samples: 24K of event 'instructions'
# Event count (approx.): 30428312415


# perf record -i -e cycles -e instructions ./a.out
[ perf record: Woken up 5 times to write data ]
[ perf record: Captured and wrote 1.111 MB perf.data (24019 samples) ]
...
# Samples: 12K of event 'cycles'
# Event count (approx.): 11699501775
...
# Samples: 12K of event 'instructions'
# Event count (approx.): 15058023559

Cancel inherit for one event when globally enable:

# perf record -e cycles/no-inherit/ -e instructions ./a.out
[ perf record: Woken up 7 times to write data ]
[ perf record: Captured and wrote 1.660 MB perf.data (36004 samples) ]
...
# Samples: 12K of event 'cycles/no-inherit/'
# Event count (approx.): 11895759282
...
# Samples: 24K of event 'instructions'
# Event count (approx.): 30668000441

Enable inherit for one event when globally disable:

# perf record -i -e cycles/no-inherit=0/ -e instructions ./a.out
[ perf record: Woken up 7 times to write data ]
[ perf record: Captured and wrote 1.654 MB perf.data (35868 samples) ]
...
# Samples: 23K of event 'cycles/no-inherit=0/'
# Event count (approx.): 23285400229
...
# Samples: 11K of event 'instructions'
# Event count (approx.): 14969050259

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/n/ebpf-2rrcnl73ih4o1qiu6t7bdxls@xxxxxxxxxxxxxx
---

In [1], Alexei enforces BPF fd array that only no-inherit event can be
used. Unfortunately, inherit is the default setting for perf and can
only be turned off globally. We need this patch to support BPF PMU
reading feature support for perf so we can insert a no-inherit perf
event into fd array while other perf events still inherit.

[1] http://lkml.kernel.org/r/1445559014-4667-1-git-send-email-ast@xxxxxxxxxx

---
tools/perf/util/evsel.c | 9 +++++++++
tools/perf/util/evsel.h | 2 ++
tools/perf/util/parse-events.c | 7 +++++++
tools/perf/util/parse-events.h | 1 +
tools/perf/util/parse-events.l | 1 +
5 files changed, 20 insertions(+)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index ab05fa5..5566b16 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -652,6 +652,15 @@ static void apply_config_terms(struct perf_evsel *evsel,
case PERF_EVSEL__CONFIG_TERM_STACK_USER:
dump_size = term->val.stack_user;
break;
+ case PERF_EVSEL__CONFIG_TERM_NOINHERIT:
+ /*
+ * attr->inherit should has already been set by
+ * perf_evsel__config. If user explicitly set
+ * inherit using config terms, override global
+ * opt->no_inherit setting.
+ */
+ attr->inherit = !term->val.no_inherit;
+ break;
default:
break;
}
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 02a5fed..28dbac1 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -43,6 +43,7 @@ enum {
PERF_EVSEL__CONFIG_TERM_TIME,
PERF_EVSEL__CONFIG_TERM_CALLGRAPH,
PERF_EVSEL__CONFIG_TERM_STACK_USER,
+ PERF_EVSEL__CONFIG_TERM_NOINHERIT,
PERF_EVSEL__CONFIG_TERM_MAX,
};

@@ -55,6 +56,7 @@ struct perf_evsel_config_term {
bool time;
char *callgraph;
u64 stack_user;
+ u64 no_inherit;
} val;
};

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 06ff8d6..478aecc 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -740,6 +740,9 @@ do { \
case PARSE_EVENTS__TERM_TYPE_STACKSIZE:
CHECK_TYPE_VAL(NUM);
break;
+ case PARSE_EVENTS__TERM_TYPE_NOINHERIT:
+ CHECK_TYPE_VAL(NUM);
+ break;
case PARSE_EVENTS__TERM_TYPE_NAME:
CHECK_TYPE_VAL(STR);
break;
@@ -775,6 +778,7 @@ static int config_term_tracepoint(struct perf_event_attr *attr,
switch (term->type_term) {
case PARSE_EVENTS__TERM_TYPE_CALLGRAPH:
case PARSE_EVENTS__TERM_TYPE_STACKSIZE:
+ case PARSE_EVENTS__TERM_TYPE_NOINHERIT:
return config_term_common(attr, term, err);
default:
if (err) {
@@ -838,6 +842,9 @@ do { \
case PARSE_EVENTS__TERM_TYPE_STACKSIZE:
ADD_CONFIG_TERM(STACK_USER, stack_user, term->val.num);
break;
+ case PARSE_EVENTS__TERM_TYPE_NOINHERIT:
+ ADD_CONFIG_TERM(NOINHERIT, no_inherit, term->val.num);
+ break;
default:
break;
}
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index fbb16c7..70cf07f 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -67,6 +67,7 @@ enum {
PARSE_EVENTS__TERM_TYPE_TIME,
PARSE_EVENTS__TERM_TYPE_CALLGRAPH,
PARSE_EVENTS__TERM_TYPE_STACKSIZE,
+ PARSE_EVENTS__TERM_TYPE_NOINHERIT
};

struct parse_events_term {
diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 5e5d31a..64d3ba8 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -189,6 +189,7 @@ branch_type { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_BRANCH_SAMPLE_TYPE
time { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_TIME); }
call-graph { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_CALLGRAPH); }
stack-size { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_STACKSIZE); }
+no-inherit { return term(yyscanner, PARSE_EVENTS__TERM_TYPE_NOINHERIT); }
, { return ','; }
"/" { BEGIN(INITIAL); return '/'; }
{name_minus} { return str(yyscanner, PE_NAME); }
--
1.8.3.4

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